There is a continual need to detect hydrazine and hydrazine derivatives. There is an OSHA requirement to prevent exposure to hydrazine and its derivatives at concentrations greater than one part per million (1.3 mg/m.sup.3). TWA (time weighted average for 8 hours). Hydrazine and hydrazine derivatives are combustibly strong reducing agents that react violently with oxidizing agents and thus present a safety hazard. Hydrazine and hydrazine derivatives are well known components of liquid rocket fuels in conjunction with an oxidizing agent such as an oxide of nitrogen, e.g., N.sub.2 O.sub.4. Thus, at facilities where liquid-fueled rockets are prepared for flight, there is a need to provide reliable and sensitive monitoring devices and procedures to determine if hydrazine or hydrazine derivatives have been introduced into the workplace.
It is known in the art that hydrazine and its derivatives may be analyzed with iodate ion, which is reduced to iodine by the hydrazine or hydrazine derivative, and the iodine is then detected with an addition-complex type indicator such as starch or an iodination type dye precursor such as fluorescein. This procedure is deficient in that hydrazine or hydrazine derivative reacts with iodine to reduce it to iodide ion, thus reducing the sensitivity of the test.
Also known in the prior art is a detector tube device invented by Draeger which is used to detect the presence of hydrazine and volatile hydrazine derivatives in air. There are two embodiments of the Draeger device: a passive detector tube and a detector tube fitted with a hand piston pump to draw the hydrazine-laden air through the reagents. The Draeger device, whether it be the passive detector tube or the detector tube fitted with a hand piston pump, is adapted to use either one of two detecting reagent systems. One detecting reagent is the pH indicator p-bromphenol blue which changes from yellow to blue in the pH range of 3.0-4.6. The yellow acid form of the indicator is converted to the blue alkaline form by reaction with hydrazine. This reaction, however, is not specific for hydrazine since any alkaline amine or ammonia, which are usually present in emissions from hydrazine rocket fuels, will produce an identical response with p-bromphenol blue. Also, the presence of acidic volatiles will desensitize the detecting reagent.
A later modification of the Draeger hydrazine detector employs as the detecting reagent a silver salt which, upon reaction with hydrazine, is reduced to the grey-black metallic silver. A serious drawback of this detecting reagent is the expense of silver salts.